Moreno Andreo <moreno.andreo@xxxxxxxxxx> wrote: > I host a Postgresql server on Ubuntu 12.04 and I am facing server > load spikes (if I run top, it goes up to 25-30 on a 4-core system)... > In some cases, I have to restart potgresql service because users call us > complaining of the slowness, but in some cases I can leave things on > their way and I see that after a bunch of minutes (about 5-10) the > situations drops to the normality (0.50-2 load). > > The problem is, as in the most cases, the I/O, If you have confirmed that there is an I/O glut during these episodes, it is probably that a cascade of dirty cache pages caused the OS dirty pages to hit the vm.dirty_ratio percentage. If you were seeing a high number for system CPU time the below would probably not help. Make sure you are using a storage system that has a persistent cache configured for write-back (rather than write-through). Reduce the OS vm.dirty_background_bytes setting to less than the size of the persistent write cache. Make sure that vm.dirty_ratio is at least 20, possibly higher. Configure the PostgreSQL background writer to be more aggressive. If those don't do it, reduce the size of shared_buffers. -- Kevin Grittner EDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
